The human intestinal microbiome contains greater than 1000 different species totaling 1014 microorganisms and plays an important role in the maintenance of the normal physiology of the gut, including energetic metabolism, proliferation and survival of epithelial cells, and protection against pathogens. The microbiota exerts both beneficial and detrimental effects on host contributing to healthy or disease. Recently, two research teams simultaneously reported overabundance of a specific microorganism, Fusobacterium nucleatum (Fn), in colorectal carcinoma (CRC) tissues. However, it was unknown if Fn was a cause or a consequence of CRC.
Fn is an opportunistic commensal anaerobe in the oral cavity, implicated in various forms of periodontal diseases. Outside the oral cavity, it is one of the most prevalent species in extra-oral infections. It is highly prevalent in intrauterine infections associated with pregnancy complications such as preterm birth, stillbirth, and neonatal sepsis. Fn adheres to and invades endothelial and epithelial cells, a likely mechanism utilized for its systemic dissemination.